Systems and Methods for Resource Access

1. A method for sharing access to a resource among a plurality of requesters, comprising: electronically receiving a first request for access to a resource; checking whether the first request comprises an indication that an access control should be engaged; and if an indication that an access control should be engaged is associated with the first request, engaging an access control scheme.

2. The method of claim 1 , further comprising: determining whether an age of the first request exceeds a threshold; and if the age exceeds the threshold, providing the first request with an indication that an access control should be engaged.

3. The method of claim 2 , further comprising: determining whether the age exceeds a second threshold; and if the age exceeds a second threshold, engaging a second access control.

4. The method of claim 3 , wherein engaging the second access control comprises: holding pending requests until the first request is processed.

5. The method of claim 2 , wherein providing the first request with an indication that an access control should be engaged comprises: setting an access control bit in the first request.

6. The method of claim 5 , wherein engaging the access control scheme comprises: accepting requests only from requesters that have not been serviced since the access control scheme was initiated.

7. A system, comprising: a resource comprising memory capable of storing data corresponding to at least two requests; and circuitry configured to detect the presence of a forward progress screen datum in at least one of the at least two requests and, after detecting said datum, to process a number of requests selected on the basis of a requester identification from the at least two requests.

8. The system of claim 7 , wherein the system is a multiprocessor computing system.

9. The system of claim 7 , wherein the system is a computer board.

10. The system of claim 7 , further comprising: a requester device comprising memory capable of storing data corresponding to at least two requests, and wherein the requester device is configured to store data corresponding to an age of at least one particular request.

11. The system of claim 10 , wherein: the requester device further comprises circuitry configured to determine whether the age of the at least one particular request has exceeded a memory value and, if so, to alter the particular request.

12. The system of claim 11 , wherein: the particular request is configured to be altered by changing the value of a data bit in a digital request format.

13. The system of claim 11 , wherein: the circuitry configured to determine whether the age of the at least one particular request has exceeded a memory value is further configured to determine whether the age of the particular request has exceeded a second memory value, and if so, to halt transmission of requests to the resource.

14. The system of claim 7 , wherein the resource is a memory.

15. A transaction request provider, comprising: a buffer for storing data relating to transactions for processing, the buffer comprising storage for time-related information; a communications interface for allowing transmission of data to a transaction processing component; a processing element for tracking the status of at least one transaction; wherein the processing element is configured to compare the time-related information corresponding to the at least one transaction with a predetermined criterion to decide whether to transmit a request that the transaction processing component initiate transaction processing according to a fair sharing scheme.

16. The transaction request provider of claim 15 , wherein the transaction request provider is a microprocessor.

17. The transaction request provider of claim 15 , wherein the transaction request provider is a client node, and the communications interface is a network interface.

18. The transaction request provider of claim 15 , wherein the processing element is configured to compare the time-related information corresponding to the at least one transaction with a second criterion to decide whether to suspend the transmission of requests to the transaction processing component.

19. The transaction request provider of claim 18 , wherein the processing element is configured to resume the transmission of requests to the transaction processing component after it has received an acknowledgement that the at least one transaction has been processed.

20. The transaction request provider of claim 15 , further comprising the transaction processing component, and wherein the fair sharing scheme comprises accepting no more than one transaction from each potential requester before accepting a second transaction from any one requester.